1. Field
The present invention relates to an optical receiver, and more particularly, to a wavelength tunable optical receiver.
2. Discussion of Related Art
Optical communication refers to transmission and exchange of information by using a wavelength of light. A wavelength band usable by the optical communication depends on a light source, but is mostly limited to an infrared ray wavelength band.
Communication using an optical cable is similar to wired communication in the related art in that an optical fiber, which is a transmission medium, is used, but is similar to wireless communication in the related art in that a signal is transmitted by using light, which is a carrier wave.
Optical communication system is divided into an optical transmission apparatus and an optical communication apparatus. The optical transmission apparatus may pass through a step of a signal, optical modulation, optical amplification, optical multification, optical detection, and a signal. The optical communication apparatus is divided into an optical distribution device and an optical switching device. A basic factor of optical transmission includes a light emitting device, light receiving device, and an optical fiber.
As a light source of the optical communication transmission device, a Light Emitting Diode and a light Amplification by Stimulated Emission of Radiation (LASER) may be mainly used. The LED has a lower output and a wider wavelength width than those of the LASER, so that the LED is usable in short range communication that is low-speed modulation.
The light receiving device has a function opposite to that of a light source that is an optical device, so that the light receiving device serves to receive an optical signal and change the received optical signal to an electrical signal within a receiver. As the light receiving device used in the optical communication, a PIN Photo Diode (PD), an Avalanche Photo Diode (APD), and the like are usable.
Since a PIN optical diode light receiving device has a wide intrinsic layer, which has the simplest structure and is capable of much absorbing a photon of entering light, in a PN junction of a semiconductor, so that a fast response rate may be recorded by a high current from the outside, there may be no amplification, and efficiency may be highly improved.